Two main difficulties are encountered with counter pressure filling machines commonly used in the trade. The pressure at which they operate is often in the order of 60 to 70 pounds per square inch, and this comparatively high pressure causes some of the wine or other aerated liquid to "boil over" as filling takes place. Furthermore filling is usually effected into the bottle from near its open mouth, and this results in considerable turbulence of the liquid as it passes into the bottle with the consequential loss of carbon dioxide gas from the liquid. In order to reduce turbulence and therefore to reduce loss of carbon dioxide gas, the liquid is frequently directed against the inner walls of the bottle, but this results in a slower filling rate. One of the main objects of this invention therefore, is to provide a means and method whereby a bottle is filled with much less turbulence than theretofore, and further to use a lower pressure than heretofore, so as to reduce the boiling over effect, thus reducing and in some cases completely avoiding loss of liquid.
A second main difficulty which is encountered is oxidation of certain liquids. Delicate sparkling wines are adversely effected if they are subjected to the action of oxygen but of course there is oxygen present in a bottle before it is filled with liquid. With previously used counter pressure machines, turbulence has resulted in exposing a large amount of surface area of the sparkling wine to the effects of oxygen, and a further object of this invention is to reduce the surface area of the wine which is exposed to oxygen and thus in turn reduce oxidation of the wine, when the invention is made use of in the filling of bottles with sparkling wine.
In our copending application, Ser. No. 478,539, filed June 12, 1974, we described a bottle filling means and method the object of which was to fill still wines or other liquids with a minimum of aeration by utilising a syphon method. By using a syphon method a relatively large tube may be employed to give a large cross-sectional area for the liquid flow, and the tube may extend almost to the bottom of the bottle being filled, the liquid flowing into the bottle with very little turbulence so that there is a minimum of aeration. However a counter pressure filling device and method is essentially much more complex since the bottle is filled under pressure.